3.1. Evaluation of the different sampling strategies
when applied to the long-term online dataset
A histogram of the possible estimates of the daily nitrous
oxide emission was made for each simulated sampling strategy
that was applied to the long-term online dataset. Fig. 6
shows the histograms of the three short-term sampling strategies,
while Fig. 7 shows the histograms of the possible
emission estimates that result from implementing the longterm
weekly grab sampling strategy to the long-term, online
dataset.
For the three short-term sampling strategies shown in
Fig. 6, about 20e30% of the simulated estimates are in the
lowest quantile of the histogram. This implies that these
sampling schemes have a relatively high chance to severely
underestimate the true average nitrous oxide emission of
91 kg N2OeN d1
. However, these three distributions also have
long tails: the chance to end up with an estimate equal to the
double of the true emission is about the same as the chance to
obtain an estimate that is equal to the true emission (i.e. 2%).
In contrast, the long-term weekly grab sampling campaigns
(Fig. 7) appear to have a relatively high chance to obtain an